Cryogenic digital systems can be used in electronic systems that require voltage and current to be transferred from one temperature domain to a lower temperature domain. For example, the electronic system may include a first temperature domain at 300 Kelvin (K) and a second temperature domain at 4K. There are other temperature domains that may be used as the second temperature domain, such as 17 K. Copper conductors are used to transfer the voltage and current between components in the temperature domains. The voltage and current on the copper conductors contribute heat into the low temperature domain using two mechanisms: a first mechanism is thermal conduction and the other mechanism is electrical heating.
Heat flow to the second temperature domain in a cryogenic digital system is a concern. There is a huge efficiency factor that has to be applied to calculate the amount of energy at room temperature to pull the heat out at a second cryogenic temperature domain, such as by a cooling subsystem. Also, when using a link between one temperature domain and another temperature domain, a signal on a segment of the link in the one temperature domain may be superconducting and the signal on a segment of the link in the other temperature domain may be conducting (also referred as normal conduction).